This invention relates to a power-amplifier cell which comprises an inverting input amplifier comprising a first transistor having a collector connected to a first supply-voltage terminal via a first resistor, and an output stage comprising a second and a third transistor whose collector-emitter paths are arranged in series, their common point forming an output of the power amplifier, the second transistor having its base connected to the collector of the first transistor, and means for applying to the base of the third transistor a control signal in phase with an input signal applied to the base of the first transistor.
Such an amplifier is known from U.S. Pat. No. 3,564,281 (FIG. 7b), which relates to a fast logic inverter, and from the article "A Wide-Band Class AB Monolithic Power Amplifier" by William D. Mack in the IEEE Journal of Solid State Circuits, Vol. 24, no. 1, Feb. 1989.
U.S. Pat. No. 3,564,281 describes a logic circuit which is used for switching but not as an amplifier. The amplifier described in the above article has been designed for use with sinusoidal signals and with a substantially resistive load.